Since Russian President Vladimir Putin formally annexed Crimea last week, Russian forces have raised the heat on the Ukrainian military on the Black Sea peninsula, seizing their ships and breaking into walled military installations with armored personnel carriers.

The Ukrainian sailors, using a small rubber boat that needed several trips to ferry them to land, were greeted by hecklers on the shore. One man shouted they were "rats" fleeing a ship, while another man blasted the Russian national anthem from his car.

"We aren't rats, we aren't running," said one sailor, who only gave his first name of Yevgeny to discuss a sensitive subject. "Why should we have stayed, what would we have accomplished?"

At a naval base near the eastern Crimean port of Feodosia, two injured servicemen were taken captive Monday and as many as 80 were detained at the site, Ukrainian officials said.

With the storming of at least three military facilities in Crimea over the past three days - and the decision by some Ukrainian troops to stay employed by switching to the Russian side - it wasn't clear how many Ukrainian troops remained on the peninsula. The former chief of Ukraine's navy, who was charged with treason after he swore allegiance to Crimea's pro-Russian authorities and urged others to defect, was named a deputy chief of Russia's Black Sea Fleet.

Ukraine's acting president, Oleksandr Turchnynov, whose new government in Kiev has struggled to maintain control and cohesion, said the Defense Ministry was ordered to withdraw all servicemen in Crimea to Ukraine's mainland.

Speaking to lawmakers in the Ukrainian capital of Kiev, Turchnynov said Ukrainian troops would be evacuated with their families in response to threats from what he called occupying Russian forces.

In the Netherlands on Monday, Russian Foreign Minister Sergey Lavrov met for the first time Monday with his Ukrainian counterpart to discuss the crisis.

Lavrov, who spoke to reporters after meeting with Ukrainian Foreign Minister Andriy Deshchytsia in The Hague, where both attended an international security summit, said he outlined the steps that Moscow believes the new Ukrainian government has to make to defuse the crisis.

The meeting was the first encounter between the two ministers since last month's ouster of Ukraine's pro-Russian president and Russia's annexation of Crimea. While Russian President Vladimir Putin has said that contacts between Russian and Ukrainian officials have continued, the meeting Monday was at the highest level since the new Ukrainian government took power a month ago.

Lavrov, who also met with U.S. Secretary of State John Kerry, said he reaffirmed Moscow's demand for a constitutional reform in Ukraine that would give more autonomy to all regions of Ukraine. Russia, eager to retain its influence in Ukraine's Russian-speaking eastern regions and prevent Ukraine from joining NATO, has pushed for Ukraine to become federation - demands the new Ukrainian government has rejected.

Deshchytsia, who spoke to reporters before his meeting with Lavrov, said the Ukrainian government has remained concerned about a Russian military buildup near Ukraine's border.

"The possibility of a military invasion is very high. We are very much worried about this concentration of troops on our eastern border," he said.

Lavrov said the G-8 format has been useful in discussing global crises - such as the Iran nuclear standoff or the Syrian civil war - but said Russia "will not be clinging to this format." He added that Russia sees the broader Group of 20 nations as a more efficient format.